A Study of BL-M08D1 in Patients With Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma and Other Solid Tumors

Inclusion Criteria: 1. Voluntarily sign the informed consent form and agree to comply with the requirements of the protocol; 2. No gender restriction; 3. Age: ≥18 years and ≤75 years; 4. Expected survival time ≥3 months; 5. Diagnosed with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) and other solid tumors; 6. Agree to provide archived tumor tissue specimens or fresh tissue samples from the primary or metastatic lesions obtained within 3 years; 7. Must have at least one measurable lesion as defined by RECIST v1.1; 8. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, with no deterioration within 2 weeks prior to the first dose; 9. Toxicities from prior anti-tumor therapy have recovered to ≤ Grade 1 as defined by NCI-CTCAE v6.0; 10. No severe cardiac dysfunction; left ventricular ejection fraction (LVEF) ≥50%; 11. Organ function levels must meet the protocol-specified requirements; 12. Coagulation function: international normalized ratio (INR) ≤1.5, and activated partial thromboplastin time (aPTT) ≤1.5 × upper limit of normal (ULN); 13. Urine protein ≤1+ or ≤1000 mg/24h; 14. For premenopausal women of childbearing potential, a serum pregnancy test must be performed within 7 days prior to the start of treatment, with a negative result, and must be non-lactating; all trial participants (both male and female) must agree to use adequate barrier contraceptive measures throughout the entire treatment period and for 6 months after the completion of treatment; 15. Participants must be capable of and willing to comply with the scheduled visits, treatment plan, laboratory tests, and other study-related procedures as required by the protocol. Exclusion Criteria: 1. Received chemotherapy, biotherapy, immunotherapy, or other anti-tumor therapies within 4 weeks or 5 half-lives prior to the first dose; 2. History of severe cardiac or cerebrovascular disease; 3. Prolonged QTc interval, complete left bundle branch block, third-degree atrioventricular block, or frequent and uncontrolled arrhythmias; 4. Active autoimmune diseases and inflammatory diseases; 5. Diagnosed with another malignant tumor within 5 years prior to the first dose; 6. Unstable thrombotic events requiring therapeutic intervention within 6 months prior to the first dose; 7. Hypertension poorly controlled by antihypertensive medication; 8. Poorly controlled blood glucose; 9. History of interstitial lung disease (ILD) requiring corticosteroid therapy, or currently diagnosed with ILD, or grade ≥2 radiation pneumonitis; 10. Severe impairment of respiratory function; 11. Active central nervous system (CNS) metastases; 12. Prior or concurrent central nervous system lesions; 13. Participants with a history of allergy to recombinant humanized antibodies or human-mouse chimeric antibodies, or allergy to any excipient component of BL-M08D1; 14. Prior history of organ transplantation or allogeneic hematopoietic stem cell transplantation (Allo-HSCT); 15. Positive for human immunodeficiency virus (HIV) antibody, active tuberculosis, active hepatitis B virus (HBV) infection, or active hepatitis C virus (HCV) infection; 16. Active infections requiring systemic therapy within 4 weeks prior to the first dose of study drug; 17. Pleural, peritoneal, or pericardial effusion requiring drainage and/or accompanied by symptoms within 4 weeks prior to the first dose of study drug; 18. Imaging findings suggest tumor invasion or encasement of abdominal, thoracic, or other major vessels; 19. Received another investigational drug within 4 weeks or 5 half-lives prior to the first dose; 20. Pregnant or breastfeeding women; 21. Other conditions deemed by the investigator to be unsuitable for participation in this clinical trial.